. >> i felt exactly that way when i heard the news today that the london marathon, in a few days is going ahead as scheduled. with resilience in its mind. peter krause, assistant professor of political science at boston college. thank you for being here. i'm going to get you a scarf in a moment. more of our coverage of today's bombings at the boston marathon when we come back. [ female announcer ] your smile. like other precious things that start off white, it yellows over time. when it comes to your smile, if you're not whitening, you're yellowing. crest whitestrips whiten as well as $500 professional treatments. guaranteed. crest 3d white whitestrips. are proven to be effective pain relievers. tylenol works by blocking pain signals to your brain. bayer advanced aspirin blocks pain at the site. try the power of bayer advanced aspirin. [ beeping ] ♪ [ male announcer ] we don't just certify our pre-owned vehicles. we inspect, analyze and recondition each one, until it's nothing short of a genuine certified pre-owned... mercedes-benz for the next new owner. ♪ hurry in to your authorized